1. Field of the Invention
This invention pertains to water soluble corrosion inhibitors and use thereof in oil refineries and in other chemical industry processes, particularly in oil refinery water systems. More particularly, the invention relates to polyamine/formaldehyde reaction products as corrosion inhibitors in refinery overhead systems.
Aqueous condensates in refinery overhead systems are extremely corrosive due to the presence of hydrochloric acid from the hydrolysis of chloride salts indigenous to crude oil composition and other corrosive agents. Varying degrees of corrosion protection have been effected by the use of a variety of known oil soluble and water soluble inhibitors. Because such inhibitors generally have a relatively high degree of surface activity, their use can cause oil carryunder from the refinery overhead system into the accumulator water where it can cause a variety of problems downstream. Accordingly there is a need for corrosion inhibitors for chemical process water systems, e.g. refinery overhead systems, which do not cause emulsions which lead to oil carryunder.
2. Prior Art
The use of amines and polyamines and their reaction products with acids as corrosion inhibitors is well known. Examples of a large body of published information includes:
U.S. Pat. No. 3,280,097 discloses reaction products of amines, phenols and aldehydes as corrosion inhibitors in refineries; PA1 U.S. Pat. No. 3,294,705 discloses acid amides of alkylene polyamines as corrosion inhibitors in refineries; PA1 U.S. Pat. No. 3,649,167 discloses morpholine as a corrosion inhibitor in refineries; PA1 U.S. Pat. No. 3,762,873 discloses polyalkylenesuccinimides as corrosion inhibitors in refineries; PA1 U.S. Pat. No. 3,819,328 discloses alkylenepolyamines as corrosion inhibitors in refineries; PA1 U.S. Pat. No. 4,062,764 discloses alkoxyalkylamines as corrosion inhibitors in refineries. PA1 Ger. Offen. No. DE 3136298 discloses quaternaries of alkoxylated alkylenepolyamines as corrosion inhibitors in petroleum recovery; PA1 Richmond et al., Mater. Perform., 21(11), 45-51 disclose the use of amines to prevent corrosion in crude column overheads; PA1 Little et al., Hydrocarbon Process., 56(5), 205-7, disclose control of corrosion in crude unit overheads by an oil-soluble blend of neutralizing amines; PA1 Nathan et al., Corr./74, Int. Corros. Forum, 124/1-124/13 disclose use of neutralizing and film-forming primary and secondary amines as corrosion inhibitors in refinery overhead streams; PA1 Kato et al, Proc. Int. Congr. Met. Corros., 5th, Meeting Date 1972, 967-71, disclose alkylenepolyamines, piperazine and morpholine as corrosion inhibitors in overhead lines.
Although such prior publications disclose a variety of amines as corrosion inhibitors in refinery overhead systems, none address the problem of hydrocarbon carryunder as a result of the emulsifying tendencies of water soluble amine corrosion inhibitors.